PURPOSE: To prevent a bad influence due to an evil deed by operating one disabling operation switch out of electrical operation switches and then disabling operation of the electrical operation switches excluding one reproduction operation switch of the electrical operation switches.

CONSTITUTION: A power input switch S1 is turned on and then an angle measuring switch S4, a distance measuring switch 55, an automatic tracking switch 56, a ten key 32 etc. are operated for performing survey. When an operator leaves a measuring machine 1 during survey. a horizontal rotation switch S2 is pressed for two times within a certain amount of time, thus disabling all operation switches excluding the switch S2. In this state, even if an outsider operates the operation switch of the survey machine 1 mischievously, no influence appears at the survey machine 1. On the other hand. when the worker operates the survey machine 1 again, all operation switches are operation- enabled by pressing the switch S2 for two times within a certain amount of time.